Augmented Reality (AR) is a concept and a set of technologies for merging of real and virtual elements to produce new visualizations—typically video—where physical and digital objects co-exist and interact in real time. 3 dimensional (3D) models and animations are some examples of virtual elements that can be visualized in AR. However, AR objects can basically be any digital information for which spatiality (3D position and orientation in space) gives added value, for example pictures, videos, graphics, text, and audio.
AR visualizations typically include a means to display augmented virtual elements as a part of the physical view. AR visualizations may be implemented using for example a tablet with an embedded camera, which captures video from the user's environment and shows it together with virtual elements on its display. AR glasses, either video-see-through or optical-see-through, either monocular or stereoscopic, can also be used for viewing.
In AR, graphical tags, fiducials or markers have been commonly used for defining position, orientation and scale for AR objects. Graphical markers have certain advantages over the using of natural features. For example, graphical markers help to make the offline process for mixed reality content production and use more independent of the actual target environment. This allows content to be positioned more reliably in the target embodiment based on the position of graphical markers, whereas changes in the environment (e.g. changes in lighting or in the position of miscellaneous objects) can otherwise make it more difficult for an augmented reality system to consistently identify position and orientation information based only on the environment.